| The East Route of South-to-North Water Transfer Project is especially big infrastructureprojects that can solve the severe problem of water shortage of the northern China. And the keywater quality of the water diversion route must reach the surface water III class.Nansi Lake is animportant transmission channel and storage lake in the east route, the key to success or failure ofthe project is pollution control. Because there are many problems of water environment in NansiLake Basin, it is very hardly realized that water quality jumped from the bad V class to the IIIclass.For both to ensure the safety of water quality,and implement the economic, social andenvironment in Nansi Lake Basin coordinated development,it has important significance inresearching the total amount control for watershed water pollutants and water qualitycomprehensive improvement project.The main research contents and results of this article include:(1) The water environment status and diagnosis of water environmental problems of NansiLake Basin have been completed.First, the evaluation indicator system of water environmental carrying capacity of the Nansi lake basinis established.Based on the calculation and allocation of water environment,investigation andevaluation of the basin water resources,the quality of water environment, and the pollution controlcapacity,the water environment status has been assessed.And the causes of the pollution ofwater environment have been analyzed from the social, economic,and natural aspects.Finally thewater environmental problems in Nansi Lake Watershed were summarized. With the economyrapidly development, the industrial structure is heavy， and its pollution problem becomesprominent; The non-point source pollution becomes the main constraints to reach the waterquality standards; The water resources is very short in the dry season, and it’s difficulty toacheive links between water pollutant discharge standard and water environment fuction zonegoal; Based on the extensive economic development over the years, the structure and function ofaquatic ecosystems are damaged seriously.(2) The watershed pollution control mode of “pollution control, circle utilization andecological restoration and protection” in Nansi Lake Basin have been made. Based on the diagnosis of water environmental problems in Nansi Lake Basin and thebackground comparisons of the watershed pollution control with the developed countries, thestrategy of “pollution control, circle utilization and ecological restoration and protection” wereput forward. The total emission reduction mechanism of water pollutants, the promotionmechanism of water environmental capacity, the approach mechanism of water quality target andthe linkage mechanism of water quality target were analyzed.“Pollution control” is through the implementation of structural adjustment, cleanproduction, end treatment of the whole pollution control process, to guide and supervise thewater environmental capacity of the sewage units can basically acceptable level of pollutioncontrol;“circle utilization” is with the concept of circular economy as a guide, according to thelocal conditions to build businesses and regional renewable water recycling system, and reducewater consumption and pollutant emissions;“ecological restoration and protection” is to correctthe behavior of ecological damage in the process of economic and social development, repairthe damaged ecological environment, and protect the ecological functions of the important area;and the “pollution control, circle utilization and ecological restoration and protection” areorganic linked. A sub-basin is as the basic unit, starting from the production and living unit, endof treatment and water reuse unit, reservoirs and ponds and river of recycled water regulationand storage, lakeside zone and estuaries, lakes and the water diversion route, based on thestrategy of “pollution control, circle utilization and ecological restoration and protection”, andthe technological bottlenecks of pollution control, circle utilization, ecological restoration andprotection are broke through, the key technologies are as the support, and the water qualitycomprehensive improvement projects are made. Thus the total emission reduction of watershedpollutants is continuously progressed, the water environment capacity is continuously rising, thelinks of total reduction and quality targets are achieved. Finally, ensure the water quality of theEast Route reach the surface water III class.(3) The water quality comprehensive improvement projects of Nansi Lake Basin have beenmade.For the typical water environmental problems of Nansi Lake Basin, based on this pollutioncontrol mode and the characteristics of Nansi Lake Basin,keeped track of the whole process ofmigration and transformation of pollutants in the watershed,the water quality comprehensiveimprovement projects were developed starting from the production and living unit、the end oftreatment and water reuse unit、the reservoirs and ponds and river of recycled water regulationand storage、the lakeside zone and estuaries、the lakes and the water diversion route.In the production and living unit, the adjustment programs of industrial structure were implemented. The first industry、the second industry and the tertiary industry was respective withenvironmental、sustainable development and economic priority. And the structural reduction ofthe total of watershed pollution sources were realized from the source. In the end of treatmentand water reuse unit,the total of point sources were realized through construction projects,such asthe project of depth treatment of the industrial and urban sewage and use of recycled water, theproject of artificial wetlands which can purify sewage.In the reservoirs and ponds and river ofrecycled water regulation and storage, through the project interception and storage and guide ofrecycled water,the bloom control project of the recycled water reservoirs and ponds,and theprojects of the quality improvement of the river channels and the ecological restoration of tshorebeach,the emission reduction of projects were further achieved, and the self-purification capacityof water bodies have been increased.In the lakeside zone and estuaries,through the projects oflarge-scale returning farmland to wetlands and ecological restoration in the lakeside zone,and theproject of artificial wetlands which can purify water,the pollution loads of non-point have beenfurther reduced, ecosystems have been restored,and the self-purification capacity of lakesidesand lakes were increased.In the lakes and the water diversion route,the projects of ecologicalrestoration in Nansi Lake have been implemented, the pollution loads of endogenesis have beenreduced, and the water quality of the storage lake and water diversion route that could stablyreached surface water III class have been ensured.(4) The implementation effects of water quality improvement projects of Nansi Lake Basinhave been assessed.The capacity、pressure、quality and regulation ability of the water environment in NansiLake Basin have been evaluted.The result showes that the water quality improvement projectshave achieved significant effects from2007to2011. The proportion of the second industry hasshown an increasing trend from2000to2007and decreased from2008. Although the proportionof three industries is still not enough reasonable, the industrial structure optimization hasachieved initial success, and the industries structure has tended to improve; With the economicdouble-digit sustained growth, the water quality of Nansi Lake Basin continues to improve; Thedirect discharges of CODCrand NH3-N have dropped above percentage of32, and the totalemission reduction of the point source water pollutants has achieved renarkable results; Thequantity of water per unit GDP and industrial added value have respectively decreased above percentage of41, and the consumption of water resources has greatly reduced; In the dry season,from2010to2011, the III class has become the major category of CODCr, and from2010to2011, the standard of NH3-N in whole lake has reached the Ⅲ class; The ecological restorationof Nansi Lake has also gotten the initial success.The overall health index of ecological systemhas shown an increasing trend, and by2011the water ecological health has been in theupper-middle level.Overall, the water quality of Nansi Lake Basin has been greatly improved,and the waterecological health has been gradually restored.However， there is still facing some problems inNansi Lake basin. Such as,there are a lot of pressure to reach the standard of water qualitycomprehensively and stably, and the water ecological health of Nansi Lake Basin is notfundamentally improved. Therefore, in order to ensure that the water quality of water diversionroute could reach the standard comprehensively and stably, and achieve harmony of theeconomic development and environment protection, the science and technology and managementinnovations must be urgently to carry out in the control of non-point source pollution,therestoration of watershed ecological integrity,the emergency system construction of sudden waterpollution accident, and so on. |
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